The primary advantage that the North had over the South was manufacturing capability. The North had already had an industrial revolution and had the ability to produce better weapons and more weapons. Obviously, this was a huge advantage for the North! The South was still dependent on slavery and this hindered their ability to industrialize.

Other advantages the North had over the South include a considerably larger population, naval power, and superior military leadership.

Northern advantages included population, manufacturing, natural resources, finances, and transportation. Twenty-four northern, western and border states had a population of 23 million, containing 92% of the industry, almost all the sources of coal, iron, copper and gold, most of the railroad lines and merchant marine, and all of the Navy. This naval advantage allowed the North to conduct trade overseas, while simultaneously blockading the South. In contrast, Southern advantages included leadership, outdoorsmanship, tactics, and foreign aid. The eleven states of the Confederacy had a population of 9 million, 3.5 million of which were slaves, but the South had the ablest officers, and the population was used to being outdoors and handling firearms and horses. The largest advantage was they fought a defensive war; the North had to conquer an area almost as large as Western Europe. Additionally, the South believed that Great Britain and France would aid them in their struggle to break away from the United States, as they were dependent on cotton and tobacco. The North gained the “moral high ground” advantage when President Lincoln made the war aim specifically about abolition of slavery in the Emancipation Proclamation rather than about Southern Independence. Aiding the South became seen as supporting slavery; no European country would help. The naval blockade, lack of transport, and overwhelming numbers of troops and materiel from the North doomed the Confederacy.

One advantage the North had over the South was that the population of the North was more than double that of the south. A big population meant a larger number of enlistees to fight in the war. Another advantage was the number of factories and industries the union had making supplies for their troops greatly outnumbered that of the South. Also, the transportation system of the North clearly out-shinedthe South and was much to their advantage. Their well developed highways, canals, and railroads greatly contributed to the transportation of supplies to the troops at the fields of battle and the supply of more troops to the field.

The North had more people, manufacturing so they could make weapons, bullets, uniforms... They also had the naval capacity to shut the South off from themselves and England, their primary trading partner.

I would place the US Navy as the number one advantage, with the manufacturing capability as second and the population advantage as third.

The existence of a Navy meant the Union could blockade the ports of the Confederacy. it took a while to effect this blockade to the point it was a stranglehold but it was key to the defeat of the Confederacy, just as Winfield Scott predicted it would be in his Anaconda plan.

The industrial capacity of the North and the advantage in railroad mileage allowed the North to take advantage of its industrial advantage.

Population was critical, the Confederacy had 9 million citizens, but 3,500,000 of these were slaves, and 110,000 involved in industrial production. Union had 22 million people with 1.3 million involved in industrial production.

The U.S. had some military technological advantages, although gatling guns were not used sufficiently to make a difference, breach loading repeating rifles made a difference in a number of battles such as Gettysburg, and the US had an advantage in rifled muskets over smooth bores. There were more telegraph capabilities in the Union than Confederacy. The confederacy did launch manage to use submarines, but they had limited effect, and while the Confederacy had the first ironclad, it was quickly overwhelmed on that score by the Union, and the recapture of the Norfolk naval yards by the Union pretty much ended the Confederacy's efforts in that area.

Finally the Union had a stronger conception of a nation, the Confederacy less so, which meant it was forced to try and defend all of its sprawling territory rather than trying to prioritize, stretching its already thin manpower resources even thinner.

The confederacy prided itself on having better battle elan, and espirit de corps, but if you actually look at the battle spirit of Union forces, you will see that they rivalled that of their southern adversaries.

The advantages the North had over the South during the American civil war were that the North had much greater manufacturing capability. The North had vast industries while the South still had plantations and agriculture. Also, the North had better generals that were veterans from previous wars or graduates from West Point.